Restored Virtaankoski draws record run of endangered Lake Päijänne trout

Restoration work at Sysmä’s Virtaankoski has succeeded beyond early expectations, with more than 580 endangered Lake Päijänne trout recorded ascending the rapids in their first spring after the €3 million upgrade.

Virtaan osakaskunta’s fisheries supervisor Markku Lepistö said the trout’s rapid acceptance of the newly restored channel bodes well for the coming spawning season.

“The most important judges have already approved the site,” Lepistö said. “The fish are voting with their fins.”

Between March and June, 90 of the 117 anglers who purchased permits reported landing a total of 583 trout, though the true figure may be higher because of possible duplicate catch reports.

Kymijoen vesi ja ympäristö ry, which monitors water quality and fish stocks, said its first post-restoration survey netted several stocked trout, indicating the habitat is functioning as designed.

Researcher Matias Hyrsky cautioned that definitive proof of successful spawning—juvenile trout—will not appear until autumn 2027, when biologists complete their next round of electric test fishing.

Last autumn WWF’s live fish camera at the site captured clear signs of spawning activity, and Hyrsky said conditions remain favourable.

“The restoration was well executed and water quality is good enough for trout,” he said.

Juvenile trout observed this spring measured 10–15 cm and were predominantly adipose-fin clipped, meaning they were hatchery-reared from wild Päijänne broodstock the previous year.

Lepistö noted that fish that survive to spawn naturally carry the strongest genes for resilience, giving the lake’s long-term trout population a boost.

Virtaankoski’s restoration, completed in spring 2025, removed an old hydropower dam and reopened a historic migration route to Tainionvirta after decades of closure.

To keep spawning gravel clean, managers plan to use a mechanical rake to remove silt and humus that can smother trout eggs.